feat: ensure Ubuntu Noble is properly supported by the Dokku release process

Also update doc references to use 24.04 in examples where possible.

docs/getting-started/install/digitalocean.md

@@ -6,7 +6,7 @@
 
 1. Login to your [DigitalOcean](https://m.do.co/c/fe06b043a083) account.
 2. Click **Create a Droplet**.
-3. Under **Choose an image > Marketplace**, search latest **Dokku** release for Ubuntu 20.04 _(version numbers may vary)_.
+3. Under **Choose an image > Marketplace**, search latest **Dokku** release for Ubuntu 24.04 _(version numbers may vary)_.
 4. Under **Choose a size**, select your machine spec.
 5. Under **Choose a datacenter region**, select your region.
 6. Add an SSH Key.

docs/getting-started/install/dreamhost.md

@@ -19,7 +19,7 @@ source openrc.sh # Set the environment variables for DreamHost Cloud
 
 This allows OpenStack client to connect to DreamHost API endpoints.
 The command below creates a new server instance named `my-dokku-instance`
-based on Ubuntu 20.04, with 2 GB RAM and 1 CPU (the flavor called
+based on Ubuntu 24.04, with 2 GB RAM and 1 CPU (the flavor called
 `supersonic`), opening network port access to HTTP and SSH (the
 `default` security group), and the name of the chosen SSH key. This
 key will be automatically added to the new server in the
@@ -28,7 +28,7 @@ be reused by Dokku.
 
 ```sh
 openstack server create \
-  --image Ubuntu-20.04 \
+  --image Ubuntu-24.04 \
   --flavor gp1.supersonic \
   --security-group default \
   --key-name $YOUR_SSH_KEYNAME \

docs/getting-started/installation/index.md

@@ -9,7 +9,7 @@ Dokku is an extensible, open source Platform as a Service that runs on a single
 To start using Dokku, you'll need a system that meets the following minimum requirements:
 
 - A fresh installation of any of the following operating systems:
-    - [Ubuntu 20.04/22.04](https://www.ubuntu.com/download)
+    - [Ubuntu 20.04/22.04/24.04](https://www.ubuntu.com/download)
     - [Debian 10+ x64](https://www.debian.org/distrib/)
 - A server with one of the following architectures
     - AMD64 (alternatively known as `x86_64`), commonly used for Intel cloud servers